Make mod+resize work in any direction
Make mod+resize work in any direction

This makes it so if you hold mod and right click on a surface to resize
it, the resize direction is chosen based on which quarter of the surface
you've clicked. The previous implementation only resized towards the
bottom right.

taiyu-len/sway,ascent12/sway,taiyu-len/sway,1ace/sway,1ace/sway,1ace/sway,ascent12/sway,ascent12/sway,SirCmpwn/sway,taiyu-len/sway